GB2373714A

GB2373714A - Steam cooker having a ventilating fan with openings therein

Info

Publication number: GB2373714A
Application number: GB0127811A
Authority: GB
Inventors: Tassan Mangina; Riccardo Furlanetto
Original assignee: Electrolux Professional SpA
Current assignee: Electrolux Professional SpA
Priority date: 2000-11-20
Filing date: 2001-11-20
Publication date: 2002-10-02
Anticipated expiration: 2021-11-20
Also published as: ITPN20000039U1; ES1051357U; DE20118239U1; FR2817020B3; ES1051357Y; FR2817020A1; IT251758Y1; GB0127811D0; GB2373714B

Abstract

Oven 11 for the steam cooking of foodstuffs comprising a radial ventilating fan for the recirculation of the air/steam mixture within the cooking chamber, an inlet 15 for the aspiration of fresh exterior air and a pipe 14 which connects the said inlet to the zone 17 behind the ventilating fan, equipped, peripherally, with a plurality of blades 3 extending radially, with an annular rear surface (5, Fig 2) and with a plurality of openings 9 designed to connect the said zone 17 with the space within the said blades. Within the ventilating fan is disposed a wall (1, Fig 2) defined externally by a continuous rim (6, Fig 2) connected the said annular rear surface by a cylindrical connecting surface (7, Fig 2) within which the said openings are disposed. The openings may be of any shape, including the shape of a parallelogram, and variously distributed over the connecting surface.

Description

IMPROVED COOKING OVEN

HAVING A VENTILATING FAN AND DEFLECTORS

The present invention relates to an oven for the steam cooking of foodstuffs, 5 in particular for institutional use, equipped with a special ventilating fan for the recirculation of the mixture of gas present in the cooking chamber and for the aspiration of dry air from the exterior atmosphere.

Ovens designed for the steam cooking of foodstuffs are known which comprise, in addition to the conventional properties and devices for cooking, the additional 10 possibility of controlling, more or less effectively, the level of humidity present in the cooking chamber; when the said humidity falls below a particular level, a water boiler associated with the said ovens is usually automatically activated and produces a flow of steam which is introduced into the said cooking chamber, thus raising the level of humidity therein. 15 Conversely, when the humidity level is too high, it is known to add to the mixture of damp gases present in the cooking chamber, comprising hot air and steam with or without fumes and/or gases produced by the foodstuffs being cooked, a flow of cool, dry air aspirated from the atmosphere.

The introduction of the cool exterior air is normally achieved by employing

20 the oven's own recirculation ventilating fan, and the pipe that introduces the exterior air is caused to open directly behind the said ventilating fan, in a manner such that the aspirating effect of the latter is also used to aspirate the exterior air by means of the said pipe in what is considered the most efficient manner.

However, the effect of the aspiration of dry exterior air is somewhat limited, 25 given that the said ventilating fan is a radial ventilating fan, generally designed to aspirate the gas from the axial front region and to blow it radially from its outer perimeter, whence the said gas returns, by means of appropriate paths and piping, into the cooking chamber.

In order to perform the said function better, the ventilating fan is equipped, towards its rear zone, with a wall that is often completely continuous and prevents 30 effective aspiration of cool exterior air by means of the said pipe.

In order to improve the said situation, it is known, for example from the European Patent No. 0926449 in the name of

-2 ELOMA GMBH GROSSKUECHENSTECHNIK, to produce a ventilating fan in which (to quote from the wording of the characterizing clause of Claim 4 of the said patent):

"... at least one fresh air supply opening (33) is provided for a plurality of openings (27) is provided for in the rear front 5 end [sic] of said ventilating fan (9) turned away from the central area of said cooking space (3), and deflecting means (29) for the entering of air flow are provided in said openings (27)."

In substance, the said document discloses a type of ventilating fan provided 10 at the rear with: - openings (27), and - deflecting devices (29), the said openings and the said deflecting devices constituting distinct features but both being present in the ventilating fan as is quite clear both from the text of the said claim and 15 from the description and the associated drawings.

However, this solution, although effective, nevertheless has two disadvantages: the first relates to the ventilating fan itself, which, in the form produced, requires substantially more costly materials and methods of construction than a conventional ventilating fan, in particular because of the inclined surfaces; the second 20 disadvantage is caused by the fact that the inclined surfaces of the said deflection devices, designated by the numeral 29 in Figure 1 of the cited patent, are projecting towards the interior of the main path of the gases aspirated from the cooking chamber 12, and thus generate undesirable swirlings and, ultimately, reduced efficiency of aspiration of the said gases from the cooking chamber.

25 The need therefore arises to provide a ventilating fan for a steamcooking oven which can be produced without excessive costs but which also permits the simultaneous aspiration both of the gases from the cooking chamber and of the air aspirated from the rear zone of the ventilating fan, their mixing and their reintroduction

into the cooking chamber, but without the said dual aspiration causing a reduction in one 30 of the two separate flows of gas.

According to the present invention there is provided an oven for the steam cooking of foodstuffs comprising:

-3 a radial ventilating fan for the recirculation of the steam or of the air/steam mixture within the cooking chamber, which is connected to the front side of the said ventilating fan, an inlet for the aspiration of fresh exterior air and a pipe which connects 5 the said inlet to the zone disposed behind the said ventilating fan, which is equipped, on the peripheral zone, with a plurality of blades and an annular rear surface, the said ventilating fan being additionally equipped with a plurality of openings designed to connect the said zone, disposed behind the said ventilating fan, with 10 the peripheral portion of the said ventilating fan that contains the said blades, wherein the said ventilating fan is provided with a wall substantially orthogonal to its axis of rotation, that the said wall is defined peripherally by a continuous rim which is connected to the said annular rear surface by means of a connecting surface disposed in a more inward position relative to the said annular rear surface, 15 and in that the said openings are disposed within the said connecting surface. The invention can be given specific form in accordance with a preferred and non-limiting example of embodiment described here in detail and illustrated solely by way of non-limiting example with reference to the attached figures, in which: 20 Figure 1 shows a view in median section in a vertical plane passing through the axis of the ventilating fan; Figure 2 shows an enlargement of the ventilating fan illustrated in Figure 1; Figure 3 shows a perspective view of a ventilating fan according to the invention, taken from a posterior diagonal angle; 25 Figure 4 shows a perspective view of the same ventilating fan, taken from an anterior diagonal angle; and Figure 5 shows an improved alternative embodiment of a ventilator wheel according to the invention.

The invention is substantially based on the following considerations: given 30 that the purpose is to cause two separate flows of gases, one aspirated from the front and one from the rear, to converge within the ventilating fan, and given that in any case the ventilating fan must have a wall orthogonal to its axis in order to transmit the motion to the peripheral blades in order to prevent the two flows of gas from intersecting without being

-4 aspirated by the blades, a wall 1 is produced which is orthogonal to the axis X of the ventilating fan and on which is affixed the hub 2 wedged on the drive shaft (not shown); the ventilating fan is equipped with a plurality of blades 3, of conventional type, connected at the front and rear to two annular plane surfaces orthogonal to the said axis X and 5 coaxial, 4 and 5 respectively.

The said wheel l, in the form of a circle, possesses a circumference 6 which constitutes its continuous rim; according to the invention, a connecting surface 7 is provided, having as its axis the same axis X as the ventilating fan, defined at the front by the said circumference 6 and at the rear by the inner rim 8 of the said flat annular surface 5, 10 disposed at the rear.

On the said connecting surface 7 are provided a plurality of through openings 9 which, given the construction of the said cylinder, are very close to and directly facing the inner edges 10 of respective blades 3.

With reference to Figure 1, the said blade is disposed in an oven for the 15 cooking of foodstuffs 11 and specifically in the zone thereof lying behind the cooking chamber 12, in a manner such that the front side 13 of the said ventilating fan is directly accessible by the gases contained in the said cooking chamber.

On the rear side of the ventilating fan is disposed a pipe 14 equipped at one end with an inlet 15 open to the exterior atmosphere and at the other end with an outlet 20 aperture 16 which enters the zone 17 of the oven immediately behind the said ventilating fan. In this way, the dry exterior air is aspirated through the said pipe 14 by the radial ventilating fan and enters the rear zone 17 thereof, whence it can pass through the said openings 9 to enter the space within the blades; here, the said dry exterior air can 25 freely mix with the moist gas aspirated from the interior of the cooking chamber 12 and continuously form a mixture of gas which is recirculated by the said radial ventilating fan within the said cooking chamber, being driven radially by the said blades 3.

For reasons of design and function, it is moreover preferable for the said connecting surface 7 to be a cylindrical surface, as shown in the figures, although it is 30 possible to find different and nevertheless advantageous shapes for the latter, such as, for example, a frustoconical shape.

It will also be appreciated that, in order to improve the efficiency of aspiration of the dry exterior air, the said opening is disposed as close as possible to the -

-5 said connecting surface, so as to reduce to a minimum the distance travelled by the dry exterior air from the said aperture 16 to the said openings 9.

In a ventilating fan according to the description given there will thus be no

swirling at the junction point between the flows of gas originating from the cooking 5 chamber and from the exterior, given that the said flows in that zone have already substantially been deflected in order to follow the same radial direction; furthermore, any device or deflector which in any way obstructs the flow of gas originating from the cooking chamber is avoided.

As a final improvement, to optimize the production of the said openings by 10 increasing their total surface area, it is desirable for the latter to be in the shape of rectangles, or at least parallelograms, and in particular, as shown diagrammatically in Figure S. they are produced by simply removing entire rectangular sectors 19 as wide as the entire width "h" of the said connecting surface 7.

Claims

-6 CLAIMS

1. Oven for the steam cooking of foodstuffs comprising: a radial ventilating fan for the recirculation of the steam or of the air/steam 5 mixture within the cooking chamber, which is connected to the front side of the said ventilating fan, an inlet for the aspiration of fresh exterior air and a pipe which connects the said inlet to the zone disposed behind the said ventilating fan, which is equipped, on the peripheral zone, with a plurality of blades and an 10 annular rear surface, the said ventilating fan being additionally equipped with a plurality of openings designed to connect the said zone, disposed behind the said ventilating fan, with the peripheral portion of the said ventilating fan that contains the said blades, wherein the said ventilating fan is provided with a wall substantially orthogonal to its axis of rotation, 15 that the said wall is defined peripherally by a continuous rim which is connected to the said annular rear surface by means of a connecting surface disposed in a more inward position relative to the said annular rear surface, and in that the said openings are disposed within the said connecting surface.

2. Oven for the cooking of foodstuffs according to Claim 1, wherein the said connecting surface is a substantially cylindrical surface, so that the said openings are disposed orthogonally to the respective radials.

25

3. Oven for the cooking of foodstuffs according to Claim 2, wherein the said outlet aperture of the said pipe is disposed, behind the said ventilating fan, in the position closest to the said connecting surface, in a manner such as to reduce to a minimum the distance travelled by the dry exterior air from the said aperture to the said openings.

30

4. Oven for the cooking of foodstuffs according to any one of the preceding claims, wherein the said openings have the shape of a parallelogram, in particular a rectangle.

S. Oven for the cooking of foodstuffs according to Claim 4, wherein the said rectangular openings are constituted by rectangular sectors as wide as the entire width of the said connecting surface.

5 6. An oven constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.