GB2317689A - Infra-red ovens - Google Patents

Abstract

An infra-red ray oven whose housing comprises two frusto-conical housing sections (1,2) spaced apart by a cylindrical housing section (3). This cylindrical section is secured to one frusto-conical housing section and includes a frontal opening (10) for access to the oven housing interior. A generally vertically arranged gas burner (4) is positioned within the lower part of the oven housing and operates to heat to red heat a frusto-conical irradiating element (5) comprising a plurality of co-axial discs. The lower orifice of the element is located immediately above the burner. A grid (9) is secured to one frusto-conical housing section and supports products to be heated by infra-red rays reflected from the surfaces of the irradiating element. The central cylindrical part of the oven is shaped to include a door which includes at least one wing (11) connected to a fixed structure of the central housing section by hinges.

Description

INFRA-RED OVENS The present invention relates to infra-red ovens and more especially, but not exclusively, to infra-red ovens for cooking and heating rolls, toasted sandwiches, bruschettes and the like.

As is well known, food products which comprise one or more slices of bread filled with, for example, salted meats, cheese, vegetables or other things, require to be cooked au gratin on both surfaces.

The action of cooking au gratin is presently carried out using as heating elements electrical resistors traversed by current or gas burners; in both systems infra-red rays are emitted, which strike the products to be heated.

The features of ovens suitable for cooking filled slices of bread au gratin are varied but they essentially comprise a plate, made of refractory material, on which the products to be cooked are placed.

In the case of cooking bruschette au gratin or when rolls have to be heated, it is required that these products should not always present the same surface to the source of heat, as a result of which it becomes necessary for the operator periodically to turn the product so that the outer surfaces of the slices are cooked evenly.

A satisfactory embodiment of an infra-red ray oven particularly suitable for the above-mentioned uses, that is to say capable of providing uniform cooking on both surfaces, or bruschettes and filled rolls, without it being necessary to turn the same during cooking, is described and claimed in the Italian model of use no. 211.0040 deposited on 24/09/86 by the applicant.

This infra-red ray oven comprises two housing sections placed one above the other and spaced from each other by a cylindrical housing section.

The oven includes a gas burner operable to heat to red heat a frusto-conical element whose lower orifice is positioned immediately above the burner.

On becoming red hot, the element emits infra-red rays which are reflected by the internal walls of the two frusto-conical housing sections onto products to be cooked placed on a horizontal grating within the oven.

Because the level of the grating is positioned to correspond with the middle housing section and in the direction of the infra-red rays, products placed within the oven are cooked substantially uniformally on both surfaces.

The present invention sets out to provide infra-red ray ovens constructionally and functionally preferable to the oven referred to above.

According to the present invention there is provided an infra-red ray oven whose housing comprises two frusto-conical housing sections spaced apart by a cylindrical housing section secured to one frusto-conical housing section and including a frontal opening for access to the oven housing interior, a generally vertically arranged gas burner positioned within the lower part of the oven housing to heat to red heat a frusto-conical irradiating element comprising a plurality of co-axial discs and whose lower orifice is located immediately above the burner, a grid secured to one frusto-conical housing section for supporting products to be heated by infra-red rays reflected from the surfaces of the irradiating element, the central cylindrical part of the oven being shaped to include a door which includes at least one wing connected to a fixed structure of the central housing section by hinges.

The door of the central cylindrical section of the oven housing may be formed of two symmetrical wings which open towards the exterior of the housing itself.

Preferably, the angular development of the opening door is equal to or slightly greater than half the external circumference of the housing.

This makes possible, when the two wings are fully open, the extraction of the internal circular grid and the lower frusto-conical section cone part of the housing.

In this way there is the advantage that the operations of cleaning the various components of the oven can be carried out while keeping the entire burner unit (including venturi tube, pilot light, control valves, ignition and control) tap fixed; a condition envisaged by safety regulations which require the elimination, as far as possible, of flexible gas hoses.

The irradiation element is movable and is simply attached to the upper frusto-conical section during operation of the oven, while for cleaning it can be raised and placed in an upper position which removes it from the burner zone of the oven.

The irradiating element has inside its frusto-conical shape a number of small discs, placed co-axially on the axis of the said element. These discs operate to control the speed of flow of the gases.

Laboratory tests have shown that the most satisfactory disc shape is one which presents a convex surface towards the lower part of the oven: this shaping has the advantage of preventing the formation of residual pockets of gas in the vicinity of the junction of each disc with its central supporting pin.

A venturi tube of the oven includes in its upper part a collar which has the purpose of ensuring that the lower base of the irradiating element is in line with the axis of the venturi tube and the application of a flame-breaking profile below an upper closure mesh of the tube.

The optimum conformation of the flame breaker is the one made with three pins each having one end in common and each arranged radially and spaced at 1 200 to its neighbours.

The upper frusto-conical oven section and the cylindrical oven section can be raised for cleaning of the oven interior.

Two different anchoring points are provided for this purpose, a fixed lower one which supports the lower frusto-conical oven housing section and an upper movable one which supports the vertically movable upper frustoconical housing section.

The movable anchoring point includes elastic contracting elements placed inside supporting columns of the lowerfrusto-conical housing section.

The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings in which: Figure 1 illustrates a front view partly in section of an oven in accordance with the invention in its operating position; Figure 2 is a side view partly in section of the oven shown in Figure 1 in its operating position; Figure 3 is a front view partly in section of the oven shown in Figure 1 with its central irradiating element raised; Figure 4 is a section taken along line IV-IV of Figure 3; Figure 5 is a side view in section of a burner zone of the oven illustrated in Figure 1; Figure 6 is a bird's eye view in section of a venturi tube of the illustrated oven; Figure 7 is a plan view of the venturi tube shown in Figure 6; Figure 8 is a front view in section of a truncated cone irradiating element of the illustrated oven; Figure 9 is a detail in section of the element shown in Figure 8; and Figure 10 is a side view of the illustrated oven with its upper part raised.

The infra-red oven illustrated in Figures 1 to 4, comprises a housing having upper and lower frusto-conical sections 1, 2 spaced apart by a cylindrical section 3. A gas burner 4, is disposed generally vertically and is positioned such that its flame is directed onto and heats to red heat a refractory irradiating element 5 of slightly truncated cone shape. The element 5 includes a mesh made of metal lathing which is positioned with its lower orifice immediately above the burner 4 and is held in place by a ring 7 integrai with the mesh.

On reaching red heat, the element 5 emits infra-red rays which are reflected by the inner walls of the conical sections 1, 2 on to products 8 to be cooked placed on a grating 9. The grating is arranged horizontally within the oven and rests on and is anchored to the lower section 2.

The central cylindrical section 3 is anchored to the upper conical section 1 and includes an opening 10 through which the products 8 can be placed in and removed from the oven. The opening 10 is shaped to define a door which comprises two symmetrically positioned pivotable wings 11, each having an angular development slightly greater than the central section 3. The wings 11 are connected to a fixed section 1 2 of the central section 3 by hinges 13.

This construction permits, when the door wings 11 are fully open, easy extraction of the grid 9 and of the lower conical section 2. Section 2 is simpiy supported on a cap 1 4 which is rotatable about the axis of the oven, thereby assisting internal cleaning of the oven.

The conical central irradiation element 5 is separable from the rest of the oven body and is free to move vertically along the axis of the oven. The element 5 has projections 1 5 which, as shown in Figure 1, are supported on rods 1 6 integral with a wall of a chimney 1 7 during operation of the oven.

When the oven is not operating and for cleaning of the grid 9 or work on the burner 4, the element 5 is raised to the position shown in Figure 2 in which it is supported by rods 18 positioned inside the chimney 17 but above the rods 16.

As shown in Figure 9 the irradiating element 5 includes a plurality of co-axial discs 1 9 positioned within the frusto-conical body 20 of the element, each shaped to have a downwardly facing convex face which assists extraction of smoke from the lower part of each disc.

The burner 4 has a venturi tube whose upper rim 21 is positioned immediately below a drilled plate 22 covered by a collar 23. A flame breaker 24 comprising three small diameter radial and equi-spaced pins is positioned below the drilled plate 22.

The flame breaker makes the flame emitted from the burner more homogeneous and retains the flame at the exit from the venturi tube.

The oven may be shaped to make it possible simultaneously to raise the frusto-conical section 1 and the central cylindrical section 3, as shown in Figure 10.

As shown in Figure 10, the supporting structure 25 of the oven has a fixed lower member including a traverse 26 on which is carried the lower conical section 2 and a gas control unit 27. The supporting structure also has a movable section which includes a traverse 29, which supports the upper conical section 1. The structure 25 is formed with a series elastic contracting elements 30 into which locking members 31 can selectively be inserted through window 28 to raise and lower the upper conical section 1 and the central section 3.

It will be appreciated that the foregoing is merely exemplary of ovens in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention as set out in the appended claims.

Claims (8)

1. An infra-red ray oven whose housing comprises two frusto-conical housing sections spaced apart by a cylindrical housing section secured to one frusto-conical housing section and including a frontal opening for access to the oven housing interior, a generally vertically arranged gas burner positioned within the lower part of the oven housing to heat to red heat a frusto-conical irradiating element comprising a plurality of co-axial discs and whose lower orifice is located immediately above the burner, a grid secured to one frusto conical housing section for supporting products to be heated by infra red rays reflected from the surfaces of the irradiating element, the central cylindrical part of the oven being shaped to include a door which includes at least one wing connected to a fixed structure of the central housing section by hinges.

2. An oven as claimed in Claim 1 wherein the irradiating element is produced from a refractory material.

3. An infra-red ray oven as claimed in Claim 1 or Claim 2 wherein means are provided for moving the irradiation element independently of the oven substantially vertically along the longitudinal axis of the oven housing.

4. An oven as claimed in Claim 3 including a chimney from whose internal walls project rods for supporting the irradiation element in a first position during operation of the oven and in a second position when the oven is not in operation.

5. An oven as claimed in any one of the preceding Claims further comprising a venturi tube which supports a flame-breaker comprising a plurality of equidistant radial pins.

6. An oven as claimed in any one of the preceding Claims, wherein the co-axial discs are placed inside the irradiating element and are shaped to have downwardly facing convex faces.

7. An oven as claimed in any one of the preceding Claims, wherein the means for moving the irradiation element comprises a supporting structure for the oven housing sections.

8. An infra-red oven substantially as herein described and as described with reference to Figures 1 to 10 of the accompanying drawings.